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'Step Out From the Old to the New"
IS 15505 (2004, Reaffirmed 2010) : Gaseous Fire
Extinguishing Systems--HCFC Blend A Extinguishing Systems.
ICS 13.220.10
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Invent a New India Using Knowledge
Bhartrhari — Nitisatakam
"Knowledge is such a treasure which cannot be stolen"
FiEAFFSRa^ED
18 15505:2004
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Indian Standard
GASEOUS FIRE EXTINGUISHING SYSTEMS -
HCFC BLEND A EXTINGUISHING SYSTEMS
ICS 13.220.10
©BIS 2004
BUREAU OF INDIAN STANDARDS
MANAK BHAVAN, 9 BAHADUR SHAH ZAFAR MARG
NEW DELHI 110002
September 2004 Price Group 7
Fire Fiohtiiis, Sectional Committee, CED 22
FOREWORD
This Indian Standard was adopted by the Bureau of Indian Standards, after the draft finalized by the Fire
Fighting Sectional Committee had been approved by the Civil Engineering Division Council.
It is important that the fire protection of building or plant be considered as a whole. HCFC blend A total
flooding systems form only a part, though an important part, of the available facilities. However, it should not
be assumed that their adoption necessarily removes the need to consider supplementary measures, such as the
provision of portable fire extinguisher or mobile appliances for first air or emergency use, or measures to deal with
special hazards.
HCFC blend A is recognized as effective for extinguishing Class A and Class B fires where electrical risks
are present. Nevertheless, it should not be forgotten in the planning of the comprehensive schemes that there
may be hazards for which this technique is not suitable, or that, in certain circumstances or situation, there may
be danger in its use, requiring special precautions. Advice on these matters can be obtained from organizations
involved with the installation of HCFC blend A total flooding systems.
System in complete shall be approved by any recognized/independent authority. Agent dump/discharge test
be replaced by enclosure integrity test unless required by legal requirement.
For the purpose of deciding whether a particular requirement of this standard is complied with, the final
value, observed or calculated, expressing the result of a test or analysis, shall be rounded off in accordance with
IS 2 : 1960 'Rules for rounding off numerical values ( revised )\ The number of significant places retained in
the rounded off value should be the same as that of the specified value in this standard.
IS 15505 : 2004
Indian Standard
GASEOUS FIRE EXTINGUISHING SYSTEMS -
HCFC BLEND A EXTINGUISHING SYSTEMS
1 SCOPE
1.1 This standard sets out specific requirements
for the design and installation of total flooding
fire-extinguishing systems employing HCFC blend A
gas extinguishant. This standard is applicable to
single supply as well as distributed supply
systems.
1.2 This standard complements various general
requirements applicable to all types of gaseous
fire-extinguishing systems ( Halocarbon as well as
Inert gas systems ) listed in IS 15493. As such, both
these standards should be read together before
designing a system. Where requirements in both
the standards differ, this standard shall take
precedence.
1.3 This standard covers total flooding systems
of HCFC blend A operating at nominal pressures of
2.5 MPa and 4.2 MPa only at 2 rC.
2 REFERENCE
The standard given below contains provisions which
through reference in this text, constitute provisions
of this standard. At the time of publication, the
edition indicated was valid. All standards are
subject to revision, and parties to agreements based
on this standard are encouraged to investigate the
possibility of applying the most recent editions of
the standard indicated below:
IS No.
Title
15493 :2004 Gaseous fire extinguishing
systems — General requirements
3 GENERAL INFORMATION
3.1 Application
3.1.1 HCFC blend A total flooding system is designed
to develop a controlled atmosphere in an enclosed
space and extinguishes the fires by cooling the flame
and breaking the free radical chain reaction and
thereby interfering with the combustion process.
The appropriate HCFC blend A concentration
shall also be maintained until the temperature
within the enclosure has fallen below the re-ignition
point.
3.1.2 The minimum HCFC blend A concentration
necessary to extinguish a flame has been determined
by experiments for several surface-type fires
particularly those involving liquids and gases. For
deep-seated fires, longer soaking times may be
necessary but are difficult to predict.
3.1.3 It is important that concentrations are not
only achieved but also maintained for a sufficient
period of time to allow effective emergency action by
trained personnel. This is equally important in all
classes of fires since a persistent ignition source can
lead to a recurrence of the initial event once the HCFC
blend A has dissipated.
4 GAS CHARACTERISTICS AND PROPERTIES
4.1 HCFC blend A is a colourless, electrically non-
conductive gas with a citrus like odour and with a
density approximately three times that of air.
4.2 HCFC blend A total flooding system can be
used to extinguish all classes of fires. Information
on use and limitations of HCFC blend A is available
in IS 15493.
4.3 HCFC blend A gas is a blend of various gases,
the composition of which is as shown in Table 1 .
4.4 HCFC blend A is a blend of gases liquefied at
suitable pressure and temperature, that can be stored
in a pressurized container.
4.5 HCFC blend A gas shall comply with
specification as shown in Table 2. The purity of
HCFC blend A shall be determined in accordance with
Annex A.
4.6 Physical properties of HCFC blend A gas is
shown in Table 3.
4.7 Toxicological information for HCFC blend A gas
are shown in Table 4.
4.8 Container Characteristics
The maximum fill density, container working
pressure of the HCFC blend A cylinders shall not
exceed the values provided in Table 5 for systems
operating at 2.5 MPa and 4.2 MPa respectively,
NOTES
1 For further data on pressure/temperature
relationship, Fig. 1 and Fig. 2 shall be referred.
2 Exceeding the maximum till density may result in
the container becoming liquid full. With the result that
an extremely high rise in pressure occurs with small
increases in temperature that could adversely affect the
integrity of the container assembly.
IS 15505:2004
Table 1 Composition of HCFC Blend A Gas
(Clauses 43 and k-\ )
SI No.
Clean Agent
Formulae
Chemical Name
Commercial Name
Tolerance
( Percent by Mass )
(1)
(2)
(3)
(4)
(5)
i)
CHCi^CFj
Dichloro trifluoro ethane ^
(HCFC- 123, 4.75 percent)
±0.5
ii)
iii)
CHCIF2
CHCIFCF3
Chloro difluoro methane
( HCFC - 22, 82 percent )
Chloro tetrafluoro ethane
( HCFC- 124, 9.5 percent)
HCFC blend A
± 0.8
±0.9
iv)
{ Detoxifier)
Iso proponyl-1 -methyl cycol-
hexane ( 3.75 percent )
±0.5
Table 2 Specification for HCFC Blend A Gas
{Clause A, 5)
SI No. Property
(1) (2)
i) Purity
ii) Moisture
iii) Acidity
iv) Non-volatile residue
v) Suspended matter or
sediment
Requirement
(3)
99.6 percent by mass, Min
1 X 1 0"^ by mass, Max
3 X 10"^ by mass, Max
0.01 percent by mass, Max
None visible
Table 3 Physical Properties
( Clause 4.6 )
SI No. Property
(1) (2)
i) Molecular mass
ii) Boiling point at 0.1 MPa
iii) Freezing point
iv) Vapour pressure at 20°C
v) Specific volume of super-
heated vapour at 1 bar
and 20°C ( mVkg )
vi) Critical temperature
vii) Critical pressure
viii) Critical volume
ix) Critical density
x) Liquid density at 20°C
xi) Saturated vapour density
at 20"C
Value
(3)
92.9
-38.3°C
<-107.2^C
825 kPa
0.259
125°C
6.65 MPa
170 cm^/mol
580 kgW
1 200 kg/m^
31 kg/m^
4.9 Pressure v^r5W5 Temperatures
To allow faster flow through piping systems, the
natural pressure of HCFC blend A is often
supplemented with dry nitrogen. Commonly used
pressures are respectively 2.5 MPa and 4.2 MPa
measured at 21°C. The respective vapour pressures
Table 4 Toxicological Information
[Clauses4n,53 andlA{d)]
SI No. Property Value
(1) (2) (3)
i) No observed adverse effect level 10 percent
( NOAEL )
ii) Lowest observed adverse effect > 10 percent
level ( LOAEL )
iii) 4 hour lethal concentration LC5Q 64 percent
Table 5 2.5 and 4.2 MPa Storage Container
Characteristics for HCFC Blend A
{Clause 4.8)
SI No. Property
(1) (2)
i) Maximum fill density
900 kg/m^
ii) Maximum container work-
ing pressure at 55'*C
iii) Superpressurization at
20°C
'2.5 MPa
(3)
0.9 kg
( litre)
3.5 MPa
Value
4.2 MPa
(4)
0.9 kg
(litre)
5.3 MPa
2.5 MPa 4.2 MPa
of HCFC blend A as well as dry nitrogen vary with
temperature.
4.10 Nitrogen Superpressurization
Nitrogen is soluble in HCFC blend A. Thus when a
storage cylinder is pressurized with nitrogen, some
dissolves in the liquid HCFC blend A and the rest
remains in the vapour phase and combines with the
vapour pressure of HCFC blend A to produce the
pressure necessary to propel the HCFC blend A
through the pipeline ( see Fig, 1 ).
5 SAFETY OF PERSONNEL
5.1 Any hazard to personnel created by the discharge
of HCFC blend A shall be considered in the design
IS 15505 : 2004
CO
2 3
111
CO
m 2
A
rt\
/
2^
•^
^^
^
,,o«^
,v*f^^
-"
%
h
—
'
._^
^ .
"^
-50 -40 -30 -20 -10 10 20 30 40 50 60
TEMPERATURE. X
Fig. 1 Pressure/Temperature Curves OF HCFC Blend A
CO
E
ui
:^
13
_j
o
>
a:
o
Q.
o
o
LU
Q-
CO
0.35
,^
-
0.3U
^
^
—
1
1
U.2b
-^
-^
0.2U
r —
0.1b
U.1U
0.05
-5
-4
-3
-2
-1
. <
)
■ 1
A
2
3
1]
'.^
A
5
■.^
.^
7
.^
ft
9
\
45 -35 -25 -15 -5
5
TEMPERATURE. X
Fig. 2 Specific Volume of Superheated HCFC Blend A Vapour at Sea Level
3
IS 15505: 2004
of the system. Potential hazard can arise from the
following:
a) Extinguishant itself,
b) Combustion products of the fire, and
c) Breakdown products of the extinguishant
resulting from exposure to fire.
5.1.1 In areas, where there is a likelihood of significant
differences between gross and net volumes of the
enclosure, utmost care shall be exercised in proper
system design to ensure that maximum concentrations
as given in 5.1(c) are not exceeded.
5.2 Where the design concentration exceeds the
LOAEL, HCFC blend A shall be used only for total
flooding in normally unoccupied areas. For minimum
safety requirements, provisions laid down in 5 of
IS 15493 shall be followed.
5.3 Toxicological information of HCFC blend A is
given in Table 4.
5.4 Miscellaneous Hazards
Some of the additional hazards are as below:
a) Cold temperatures — Direct contact with
the vapourizing liquid being discharged
from a HCFC blend A system will have a
strong chilling effect on objects and can
cause frostbite burns to the skin. The liquid
phase vapourizes rapidly when mixed with
air and thus limits the hazard to immediate
vicinity of the discharge point.
b) Visibility — Discharge of HCFC blend A
may create a light mist resulting from
condensation of moisture in the air.
However, the mist rarely persists after the
discharge is completed. Thus little hazard
is created from the standpoint of reduced
visibility. Once HCFC blend A is discharged
into an enclosure, its presence is easy to
detect through the normal senses in
concentrations above about 3 percent.
c) Uneven distribution — In total flooding
systems, the high density of HCFC blend A
vapour requires the use of discharge
nozzles that will achieve a well-mixed
atmosphere in order to prevent local
pockets of higher concentration. HCFC
blend A and HCFC blend A air mixtures are
also more dense than air and will drift and
accumulate in low spaces, such as cellars,
pits and floor voids, and may be difficult to
ventilate effectively.
6 VENTING ARRANGEMENT
Venting shall be provided at levels as high as possible
in the enclosure. Allowable pressures for average
enclosures shall be in conformity with the following
guidelines. The building requirements for the type
of enclosure and free venting required can also be
calculated from the relevant specifications.
7 EXTINGUISHING AGENT SUPPLY
7.1 Quantity
a) Quantity requirements ( main ) — The
amount of the HCFC blend A in the system
shall be at least sufficient for the largest
single hazard protected or group of
communicating hazards that are to be
protected simultaneously.
b) Quantity requirements (reserve) — Where
required, the reserve quantity should be
same as that of main supply as in 7.1(a).
However if replenishing of HCFC blend A
gas supply takes more than 7 days at the
site of installation, advice may be sought
from the authority concerned on the quantity
to be kept available as reserve.
c) Uninterrupted protection — Where
uninterrupted protection is required,
reserve supply and main supply should be
permanently connected to the distribution
piping and arranged for easy changeover to
enable uninterrupted protection.
d) The quantity of the HCFC blend A required
shall be further adjusted to compensate for
any special conditions, such as unclosable
openings, forced ventilation, the free
volume of air receivers that may discharge
into the risk, altitude ( substantially above
or below sea level ) or any other causes for
the extinguishant loss. However in no
case the injected concentration of the
HCFC blend A gas shall exceed its LOAEL
(^ee Table 4).
7.2 Total Flooding Quantity
All HCFC blend A total flooding systems shall be
capable of producing the required concentration under
the conditions of maximum net volume, maximum
leakage and minimum expected ambient temperatures.
Fig. 2 shows the specific volume of superheated HCFC
blend A vapour at various temperatures.
a) The amount of HCFC blend A required to
achieve the design concentration shall be
calculated from the following equations
and this figure shall need further
adjustment as stated in 7. 1(d):
M =
VC
5(100-C)
IS 15505 : 2004
where
M
C
total flooding quantity, kg;
design concentration, percent by
volume;
net volume of the hazard, m^;
K^+ K^iT), where K^ and K^ are constants
specific to the agent used and Tis minimum
temperature inside enclosure; and
specific volume of superheated agent at
2PC,m%g.
Specific volume constants for the HCFC blend
A gas are K^ - 0.241 3 and K^ = 0.000 88. It may
also be noted that this equation provides an
allowance for the normal leakage from a tight
enclosure to accomplish equalization of pressure.
V
S
b) The agent requirement per unit volume of
protected space can also be calculated by
using Table 6 for various levels of
concentration corresponding to the
temperature within the protected enclosure
( flooding factor obtained from Table 6 that
is temperature of the enclosure versus gas
concentration, multiplied by net volume of
the enclosure ).
NOTE — Quantity of the agent shall be the highest of
the values calculated from the provisions contained in
7.2(a) and 7.2(b),
7.3 The actual quantity of HCFC blend A gas storage
required shall be determined in the following manner,
which shall further be subject to changes for pressure
due to elevation [ see 8(g) and Table 8 ].
Table 6 Total Flooding Quantity ( HCFC Blend A )
[Clause 12(b)]
SI
Tempera-
Specific
HCFC Blend A Mass Requirements per
Unit Veil
ime of Protected
1
No.
ture
Vapour
Space
( kg/m^ )
T
Volume, S
Design Concentration
by Volume, C, Percent
T
m^/kg
r
1
8
9
10
11
12
13
14
15
16
(1)
(2)
(3)
(4)
(5)
(6)
(7)
(8)
(9)
(10)
(11)
(12)
(13)
i)
-35
0.210
0.358
0.413
0.470
0.528
0.588
0.648
0.710
0.774
0.839
0.906
ii)
-30
0.215
0.351
0.405
0.461
0.517
0.576
0.635
0.696
0.758
0.822
0.887
iii)
-25
0.219
0.343
0.397
0.451
0.507
0.564
0.622
0.682
0.743
0.805
0.869
iv)
-20
0.224
0.337
0.389
0.442
0.497
0.553
0.610
0.668
0.728
0.790
0.852
V)
-15
0.228
0.330
0.381
0.434
0.487
0.542
0.598
0.655
0.714
0.774
0.835
vi)
-10
0.232
0.324
0.374
0.426
0.478
0.532
0.587
0.643
0.700
0.760
0.819
vii)
-5
0.237
0.318
0.367
0.418
0.469
0.522
0.576
0.631
0.687
0.745
0.804
viii)
0.241
0.312
0.360
0.410
0.461
0.512
0.565
0.619
0.675
0.731
0.789
ix)
5
0.246
0.306
0.354
0.403
0.452
0.503
0.555
0.608
0.663
0.718
0.775
X)
10
0.250
0.301
0.348
0.396
0.444
0.494
0.545
0.598
0.651
0.706
0.762
xi)
15
0.254
0.296
0.342
0.389
0.437
0.486
0.536
0.587
0.640
0.693
0.748
xii)
20
0.259
0.291
0.336
0.382
0.429
0.477
0.527
0.577
0.629
0.682
0.736
xiii)
25
0.263
0.286
0.330
0.376
0.422
0.469
0.518
0.568
0.618
0.670
0.723
xiv)
30
0.268
0.281
0.325
0.369
0.415
0.462
0.509
0.558
0.608
0.659
0.711
xv)
35
0.272
0.277
0.320
0.363
0.408
0.454
0.501
0.549
0.598
0.648
0.700
xvi)
40
0.277
0.272
0.314
0.358
0.402
0.447
0.493
0.540
0.589
0.638
0.689
xvii)
45
0.281
0.268
0.310
0.352
0.395
0.440
0.485
0.532
0.579
0.628
0.678
xviii)
50
0.285
0.264
0.305
0.347
0.389
0.433
0.478
0.524
0.570
0.616
0.667
xix)
55
0.290
0:260
0.300
0.341
0.383
0.427
0.471
0.516
0.562
0.609
0.657
xx)
60
0.294
0.256
0.296
0.336
0.378
0.420
0.463
0.508
0.553
0.600
0.647
xxi)
65
0.299
0.252
0.291
0.331
0.372
0.414
0.457
0.500
0.545
0.591
0.638
xxii)
70
0.303
0.248
0.287
0.326
0.367
0.408
0.450
0.533
0.537
0.582
0.628
xxiii)
75
0.307
0.245
0.283
0.322
0.361
0.402
0.444
0.436
0.529
0.573
0.620
xxiv)
80
0.312
0.241
0.279
0.317
0.356
0.396
0.437
0.479
0.522
0.566
0.611
xxv)
85
0.317
0.238
0.275
0.313
0.351
0.391
0.432
0.472
0.515
0.558
0.602
xxvi)
90
0.321
0.235
0.271
0.308
0.346
0.385
0.425
0.456
0.508
0.550
0.594
xxvii)
95
0.225
0.232
0.267
0.304
0.342
0.380
0.419
0.450
0501
0.543
0.586
IS 15505 : 2004
7.3.1 Enclosure Volumes
The net enclosure volumes are calculated using the
following equations:
y = y _y
^ Max g '^ s'
a)
where
V.
Max
Min
maximum net volume of the
enclosure, m^;
gross volume of enclosure,
m^;
volume of the structural/similar
permanent objects in the
enclosure that gas can not
permeate, m^;
minimum net volume of
enclosure considering the
maximum anticipated volume
of the occupancy related to
the objects in the enclosure,
m^; and
F^ = volume of the occupancy
related objects in the enclosure
that gas can not permeate, for
example, furniture fittings,
etc, in m^ ( This value shall be
ignored if that volume is less
than 25 percent of the maximum
net volume F^^ J.
8 DESIGN CONCENTRATION
a) Determination of design concentration of
HCFC blend A shall include consideration
of the type and quantity of combustibles
involved, the conditions under which it
normally exists in the enclosure, and any
special conditions in the enclosure. The HCFC
blend A system design shall be capable of
establishing uniform design concentration
throughout the protected volume.
b) The distribution system for applying
HCFC blend A to enclosed hazards shall be
designed with due consideration of the
materials involved, the type of burning
expected and the nature of the enclosure,
anyone of which may affect the discharge
times and rates of application.
c) The minimum design concentration of
HCFC blend A for fires involving surface class
A, and also fires involving flammable liquids
and gases shall be as follows:
1) The minimum design concentration of the
HCFC blend A agent for Class A surface
fire hazards shall be the extinguishing
concentration ( 7.2 percent ) plus a
loading of 20 percent as a safety factor.
2) The minimum design concentration of the
HCFC blend A agent for Class B ftre
hazards shall be the extinguishing
concentration ( 7.2 percent ) with a
loading of 30 percent as a safety factor.
NOTE — Where different classes of
hazards exist, design concentration
shall be for the hazard requiring the
greatest concentration.
d) Requirements for flame extinguishment —
Tests shall be conducted in independent
recognized laboratories for the determination
of extinguishing concentration. This value
as determined shall be loaded by a safety
factor of 30 percent. In no case, shall the design
concentration be less than Z,6 percent or such
higher figure, determined by test as indicated
above.
e) Requirements for inerting
1) Minimum concentration requirements
for inerting atmospheres within the
enclosure involving flammable liquids
and gases shall be as shown in Table 7.
Where range of separate fuels is present,
the inerting concentration shall be as
shown in Table 7 for the fuel requiring
the greatest concentration.
2) For other fuels not listed in the Table 7,
tests shall be conducted in independent
recognized laboratories for the
determination of inerting concentration.
This value as determined from Table 7
shall be loaded by a safety factor of
10 percent. In no case, shall the
inerting concentration be less than 8.6
percent or such higher figure,
determined by test as indicated above.
f) Lastly, it is required to adjust the number of
HCFC blend A agent containers, where
necessary, by compensating for ambient
pressure change due to location elevation
as per 8(g) and round off the number as
before. The equation in such cases will be
as follows:
N^ = TV times atmospheric correction factor
where
yVj = adjusted number of containers, and
N = initial number of containers.
g) Atmospheric correction factors — It shall
be necessary to adjust the actual HCFC blend
A agent quantity for altitude effects.
Depending upon the altitude, atmospheric
IS 15505 : 2004
correction factor shall be applied as per
Table 8. The adjusted HCFC blend A
agent quantity is determined by
muhiplying the number of HCFC blend A
containers by the ratio of average ambient
enclosure pressure to standard sea level
pressure.
Table 7 HCFC Blend A Design Concentration
for Inerting
[ Clause 8(e) ]
SI No.
Material
Percentage
by Volume
(1)
(2)
(3)
i)
Acetone
12.0
ii)
Benzene
12.5
iii)
Methane
18.6
iv)
/?- Heptane
13.0
V)
Propane
18.3
vi)
Mythyl ethyl ketone
14.0
vii)
Iso-butane
18.4
viii)
Difluoromethane ( HFC32 )
8.6
Table 8 Atmospheric Correction Factors
[ Clauses 7.3 and 8(g) ]
SI No.
Equivalent
Enclosure
Atmospheric
Altitude
Pressure
Correction
m
mmHg
Factor
(1)
(2)
(3)
(4)
i)
-920
840
1.11
ii)
-610
812
1.07
iii)
-300
787
1.04
iv)
760
1.00
V)
300
733
0.96
vi)
610
705
0.93
vii)
920
678
0.89
viii)
1 220
650
0.86
ix)
1 520
622
0.82
X)
1 830
596
0.78
xi)
2 130
570
0.75
xii)
2 440
550
0.72
xiii)
2 740
528
0.69
xiv)
3 050
505
0.66
9 APPLICATION RATE, DURATION OF
DISCHARGE AND DISCHARGE TIME
9.1 Design Application Rate
The design application rate shall be based on the
quantity of HCFC blend A (Af^) as per 8(c) and the
duration of discharge required under 9.2.
9.2 Duration of HCFC Blend A Discharge
The minimum theoretical injected concentration shall
be achieved within 10 s and the actual injected
concentration ( that is the above plus a suitable safety
factor adjusted for container rounding off) shall be
achieved within 2 min.
9.3 Discharge Time for the HCFC Blend A Gas
The discharge time shall be the time for actuation of
the first HCFC blend A container valve to the
achievement of the required design concentration or
the discharge time is the interval from the first
appearance of liquid at the nozzle to the time when
the discharge becomes predominantly gaseous,
recognized by a change in the appearance and sound
of the discharge.
a) The discharge time period is defined as the
time required to discharge from the nozzles
90 percent of the agent mass at 21 °C,
necessary to achieve the minimum design
concentration based on a 20 percent safety
factor for flame extinguishment,
b) The discharge time required to achieve
95 percent of the minimum design
concentration for flame extinguishment based
on a 20 percent safety factor shall not exceed
10 s, and
c) Flow calculations performed in accordance
with 12, or in accordance with the approved
pre-engineered systems, shall be used to
demonstrate the discharge time requirements
stated above.
10 STORAGE CONTAINERS
10.1 The HCFC blend A storage containers shall
comply with the following in addition to various
requirements contained in IS 15493.
10.1.1 The containers used in HCFC blend A systems
shall be seamless cylinders designed, fabricated,
inspected, certified and stamped in accordance with
the requirements of Chief Controller of Explosives,
Nagpur.
10.1.2 The design pressure shall be suitable for the
maximum pressure developed at SS^'C or at the maximum
controlled temperature limit.
10.1.3 The containers shall be charged to a filling
ratio ( fill density ) not greater than 900 kg/m^ and
not less than 500 kg/m^.
10.1.4 The containers shall be superpressurized
with nitrogen (moisture content not greater than
0.005 percent by volume) to a total pressure of
either 2.5 MPa± 5 percent or at 4,2 MPa± 5 percent
measured at21 ± 1°C.
IS 15505 : 2004
1 0.1.5 The storage containers shall have reliable means
of indicating their pressure.
10.1.6 The storage containers shall have reliable
means of indicating the variation of container
pressure with temperature. A pressure/temperature
chart ( see Fig. 3 ) attached to the container, is
acceptable.
10.1.7 The requirements of authorities having
jurisdiction for containers may take precedence
over the requirements of this standard, if their
specifications are more stringent.
11 DISTRIBUTION SYSTEM
The HCFC blend A distribution system shall
comply with the following in addition to various
requirements contained in IS 15493.
11.1 Piping Network
a) The piping shall withstand the maximum
expected pressure at the maximum storage
temperature, as follows:
1) 2.5MPasystems:4.19MPaat55X
2) 4.2 MPa systems: 6.58 MPa at 55°C
b) The piping shall withstand the maximum
developed pressure at 55''C and shall be in
accordance with IS 15493.
c) Carbon steel pipes and fittings shall be
galvanized inside and outside or otherwise
suitably protected against corrosion.
Stainless steel pipes and fittings may be used
without corrosion protection.
NOTE — Stainless steel pipes may be used in all
applications subject to appropriate design strength
calculations.
11.2 Piping Fittings
the
a) Pipe fittings shall comply with
requirements given in IS 1 5493 .
b) Fittings shall be selected according to the
wall thickness or schedule number of the pipe
to which they are intended to be fitted.
11.3 Pipe Sizing
Pipe sizing is a complex issue, particularly in view of
the two-phase flow within the pipelines. Too small a
bore results in excessive pressure losses while too
large a bore reduces the liquid flow velocity. This also
may result in excess pressure drops and lower flow
rates. Table 9 may be used as a guide to estimate pipe
sizes. The sizes can be checked using an approved
computer flow calculation programme.
4.D
4.0
-
/
/
-
/
/
3.5
-
J
/
\n
D
CO
if)
us
a:
Ql
3.0
2.5
2.0
-
/
-
y
/
f
-
/
/
/
-
y
/
1 *;
Mil
Mil
nil
nil
Hit
nil
nil
ini
nil
nil
o.o
-
/
6.0
-
/
-
/
5.5
-
/
_
/
Q.
:i
^-5.0
D
CO
^ 4.5
-
/
-
>
/
-
/
4.0
-
y
-
y
/
3.5
-
/
r
_
/
3.0
>
y
_x
9 R
Till
nil
nil
nil
nil
WW
nil
nil
nil
WW
-30 -20-10 10 20 30 40 50 60 70
TEMPERATURE. °C
-30 -20 -10 10 20 30 40 50 60 70
TEMPERATURE. X
(a) 2.5 MPa nominal fill at 15X (b) 4.2 MPa NOMINAL FILL AT 15X
Fig. 3 Temperature/Pressure Variations for HCFC Blend A in Storage Containers
IS 15505 ! 2004
Table 9 Pipe Sizes versus Flow Rate ( Informative )
{Clause \\ 3)
SI No.
Nominal Bore
Minimum Flow
Maximum
Flow Rate for Equiva
ilent Lengths
mm
Rate, kg/s
of Pipe, kg/s
More Than
Between
Up to 5 m
10 m
5 and 10 m
(1)
(2)
(3)
(4)
(5)
(6)
10
0.3
0.3
0.4
0.5
ii)
15
0.5
0.5
0.7
1.0
iii)
20
1.0
1.0
1.0
2.0
iv)
25
1.5
1.5
2.7
4.0
V)
32
2.6
3.5
5.6
8,0
vi)
40
3.8
4.5
8.6
12.2
vii)
50
5.9
8.8
16.3
23.5
viii)
65
8.8
14.5
25.4
37.0
ix)
80
15.0
25.0
45.0
63.5
X)
100
26.3
50.0
90.0
131.5
xi)
125
43.0
95.0
172.0
250.0
xii)
150
57.5
150.0
272.0
408.0
11.4 Nozzle Placement
a) The type of nozzles selected, their number
and placement shall be such that the design
concentration will be established in all parts
of the protected enclosure and such that the
discharge will not unduly splash flammable
liquids or create dust clouds that could extend
the fire, create an explosion, or otherwise
adversely affect the contents or the integrity
of the enclosure.
b) Selecting the number of nozzles in a system
shall take into account, the shape of the
enclosure ( area and volume ), shape of the
void ( raised floor, suspended ceiling ),
installed equipment in the enclosure/void
( chimney effect ), allowed pressure at the
restrictor ( Pipe quality ) and obstructions,
which may affect the distribution of the
discharged agent and architectural
considerations.
c) Nozzles shall be selected and located to protect
an area less than its area of coverage. The
area of coverage to the type of nozzle shall
be so listed for the purpose.
d) In hazards having suspended ceiling,
consideration shall be given for having
nozzles installed in the ceiling void
( simultaneous discharge ) in order to equalize
the pressure during discharge, thus reducing
the risk of unnecessary damaging ceiling tiles
etc.
e) In hazards having raised floor ( not gas-
tight ) consideration shall be given for
having nozzles installed in the floor void
( simultaneous discharge ) in order to
equalize the pressure and obtain
extinguishing concentration below the floor.
f) In hazards having suspended ceiling, nozzles
for protecting rooms shall be installed in such
a way that the jets from the nozzles do not
damage the ceiling plates excessively during
discharge, that is, the nozzles to be positioned
vertically with the discharge holes free of the
ceiling tiles and/or Escutcheon plates. For
light weight ceiling tiles, it may be
recommended to securely anchor tiles for a
minimum of 1 .5 m from each discharge nozzle.
g) Maximum nozzle height above floor level for
a single row of nozzles is 3 .5 m . Where ceiling
height ( of the protected enclosure ) exceeds
3.5 m, an additional row of nozzles shall be
provided for uniform and faster distribution
of the agent within the enclosure.
h) Minimum nozzle height above the floor level
of the hazard shall be 0.2 m.
j) The maximum distance between nozzles should
not exceed 6 m and the maximum distance to
wall/partition should not exceed 3 m.
k) In case of enclosures having no false ceiling,
nozzles can be located on the ceiling anywhere
within 0.5 to 5 m from the walls. In case of
enclosures having false ceilings, deflector
shields shall be used with each nozzle and
also nozzles shall be so located ( with an
IS 15505 : 2004
anticipation of dislodgement of false ceiling
materials or any movable objects in the path
of discharge ) to prevent any damage thereto.
Nozzles shall be provided in all the concealed
spaces, floor voids, ceiling voids, etc, besides
the main area within the protected enclosure.
12 HYDRAULICS OF THE SYSTEM
12.1 General
a) An approved hydraulic calculation method
shall be employed to predict pipe sizes,
nozzle pressure, agent flow rate, discharge
per nozzle and the discharge time.
b) The various parameters as stated below shall
be considered to determine the following
minimum limits of accuracy:
1) The weight of agent predicted by flow
calculation to discharge from the nozzle
should agree with the total weight of
agent actually discharged from each
nozzle in the system within a range of
-5 to +10 percent of actual prediction.
2) The discharge time predicted by the flow
calculation method should agree with the
actual discharge time from each nozzle
in the system.
3) The accuracy of the calculated nozzle
pressures versus actual pressures at each
nozzle should be such that actual nozzle
pressures in an installation will not fall
outside the range required for acceptable
nozzle performance.
4) The nozzle pressure should not fall below
the minimum or above the maximum
nozzle pressure required for the nozzle
to uniformly distribute the agent
throughout the volume and to protect
nozzle's discharge.
12.2 Two-Phase Flow ofHCFC Blend A
The two-phase flow of HCFC blend A shall be in
accordance to Annex B of IS 15493.
12.3 Engineered and Pre-engineered Systems
a) General — HCFC blend A is suitable for use
in both engineered (central storage) systems
and pre-engineered (modular or packaged)
systems, as described in 12, 3(b) and
12.3(c).
b) Engineered — An engineered system
uses large storage containers installed in a
central location. The containers are manifold
together and a single pipe feeds the nozzle
located inside the hazard area. Predicting
pipe pressure losses and designing nozzle
orifice sizes requires complex flow
calculations for both HCFC blend A and
nitrogen phases, which takes into account
the minimum and maximum volumes or the
enclosure ( see Fig. 4 ).
c) Pre-engineered — A pre-engineered system
involves a single container with a maximum
of two nozzles and a small piping network.
This system can be multiplied to cover larger
volume areas. The larger area is viewed as a
number of smaller areas each protected by a
single modular unit ( see Fig. 5 ).
13 POST DISCHARGE SCENARIO
The HCFC blend A system, when tested for discharge
test, in accordance with the following requirements
shall be:
a) Within 1 min of commencement of discharge,
the concentrations at not more than 1 m above
the floor of the enclosure or at the top of the
highest hazard shall not vary from the design
concentration by more than 1 percent by
volume.
b) At 10 min of the discharge or other period
( as required if necessary ), the concentrations
at the levels given in 13(a) shall be not less
than 80 percent of the design concentration
( Retention time ).
14 COMMISSIONING AND ACCEPTANCE
TESTING
14.1 Criteria for Acceptance
The completed HCFC blend A total flooding
system shall be commissioned in accordance with
provisions of IS 15493 and the system's performance
proved.
14.2 Reporting
The following shall be reported:
a) Information identifying the system shall
include:
1) Installation, designer and contractor;
2) Enclosure identifications;
3) Enclosure temperature prior to
discharge;
4) Oxygen and carbon dioxide residual
concentrations; and
5) Positionof sampling points.
b) Date and time of test.
c) Discharge time.
10
IS 15505 : 2004
d) Concentration levels at each sampling point
at 2 min and 1 min from the commencement
of discharge.
e) System deficiencies.
f) Reference to this test method in accordance
with IS 15493.
CEILING
VOID
CEILING VOID
NOZZLES
EXTINGUISHANT
CONTAINERS
Fig. 4 Typical Engineered HCFC Blend A System
CEILING
VOID
INCLINED MODULES SUITABLE
FOR FLOOR AND CEILING VOIDS
CONTROL
CIRCUIT
ROOM
NOZZLE
LARGE
CONTAINERS
CONTROL
CABINET
SMALL CONTAINERS
FOR LESS ACCESSIBLE
AREAS
Fig. 5 Typical Pre-engineered HCFC Blend A System
11
IS 15505 : 2004
ANNEX A
( Clause 4.5 )
DETERMINATION OF PURITY OF HCFC BLEND A
A-1 HCFC blend A is a blend of three single
HCFC components and a detoxifier as given
in Table 1. A random sampling of 10 percent of the
production is undertaken to determine the quality
of the production.
A-2 Following the filling of production cylinder,
a 1 kg sample is removed from the selected cylinder
and stored in a sampling cylinder. A small amount of
HCFC blend A is expelled from the valve until the
liquid phase of the product is produced. A 1 litre
capacity polypropylene sampling bag is connected
to the cylinder and 2 ml of the blend is drawn into the
bag. It is essential that only liquid blend is allowed
to be sampled.
A-3 The bag together with the sample of blend is
conditioned by placing in an oven at 40°C for 20 min
in order to ensure that a homogeneous gasified
sample is produced. A sample of 1 microlitre is injected
into the column of the gas chromatograph
equipment and analysed. The percentage of each
HCFC component shall be determined from the
resulting chromatograph by comparison with the
standard graphs [ see Fig. 6(a) and 6(b) ]. The areas
of the chromatograph are measured automatically,
converted to a percentage.
A-4 The use of G.C. technique does not provide a
sufficiently accurate analysis result in respect of the
detoxifier component and therefore an additional
procedure is used to determine this parameter, using
a simple weighing technique.
A-5 The cylinder containing the remaining
sample of blend ( after determining the HCFC
content ) is weighed accurately to an accuracy of
0. 1 g. The gas phase ( HCFC ) of the sample is removed
at an ambient temperature using a gas phase recovery
technique. Care should be exercised to retain liquid
phase.
The cylinder is then placed in a water bath at a
temperature of SC'C and weighed periodically (15 min
intervals ) until a stable weight recorded.
The remaining liquid is used for determination of the
percentage weight of the detoxifying component, a
simple weighing technique being used.
An additional gas chromatography should be
performed on the resulting liquid at this stage to
confirm that no HCFC remain in the sample.
26.00
19.80
g 14.60
E
9.40
4.20 i
-1.00
0.00 6.00
Component Name
F123
X X
12.00
16.00
TIME (min.)
Retention Time [Min)
2.100
15.425
24,00
Area (%)
5.480
94.520
30.00
Fig. 6A Chrom-Card Strip-Chart of HCFC Blend A
12
0.00
IS 15505 : 2004
1400
2800
4200
5600
7000
TIME (min.)
Component Name Retention Time (M/n) Area (%)
F22 1.333 85.249
F124 3.333 9.758
F123 6.083 4.994
Fig. 6B Chrom-Card Strip-Chart of HCFC Blend A
13
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